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Topic: Relay bad ? (Read 579 times) previous topic - next topic

Relay bad ?

While driving the alternator charges at normal voltage + or - 13.5 vdc .  When I crank the generator the charge voltage from the alternator goes to 0 vdc.  Turning the generator off restores the normal charge voltage from the alternator.  I don't think this is normal , so the question is this,  Relay bad or some other problem. 
Terry and Cheryl Brown
1997 U295 36'
Build #5066
2006 Jeep TJ Rubicon
1993 BMW R100 GSPD

Re: Relay bad ?

Reply #1 –
Voltage should be higher from the alternator 14.2-14.4 and also some other problem with no voltage with  the generator running. I am sure someone will have some idea of what is going on.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Relay bad ?

Reply #2 –
This gets into a very sensitive (electrically speaking) discussion.

The source WITH THE HIGHER VOLTAGE will be the charge source assuming it has sufficient amps to reach that voltage.  So, it may be the inverter/charger when in bulk mode and likely absorption mode, then switch to alternator when inverter/charger drops to float mode.

Absolutely normal.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Relay bad ?

Reply #3 –
So where are you reading voltages from?

Re: Relay bad ?

Reply #4 –
Quote from: Barry & Cindy –
So where are you reading voltages from?

Good question.....
The dash gauge should always read the chassis or starting battery voltage, less any voltage drop associated with the wiring to the gauge itself.
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: Relay bad ?

Reply #5 –
I found the problem!!!!!  When I completed the alternator sense wire modification , I attached it to the house battery isolator terminal.  This caused a difference in potential in the 12vdc as sensed by the alternator.  I reattached  the sense wire directly to the + terminal on the chassis battery.  Now the alternator charges the chassis batteries all the time weather the generator is running or not.  Thanks for the help. 
Terry and Cheryl Brown
1997 U295 36'
Build #5066
2006 Jeep TJ Rubicon
1993 BMW R100 GSPD

Re: Relay bad ?

Reply #6 –
Thanks for the follow up! I always appreciate the closure when someone solves the problem...
Don
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Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson
 

Re: Relay bad ?

Reply #7 –
Yup, with the alternator sense wire on the house bank, with the generator running and inverter/charger charging, the sense wire tells the alternator to do nothing.  And unless the boost switch is on, the chassis battery is NOT charged from the inverter/charger.

So yes, having the sense wire on the house bank and inverter/charger charging (only) the house bank, the chassis battery will be "neglected".
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020